This invention relates to thermally responsive electrical switches and more particularly to small, compact switches which are useful as overload protectors.
Past designs of thermally responsive electrical switches employing heater and thermostatic disk assemblies such as described in U.S. Pat. Nos. 3,194,924 and 3,104,296 assigned to the assignee of the present application have been successful and particularly well suited for protective use in connection with electrical apparatus such as encountered in motors and the like. However, tight response tolerance in present designs of motors and the like require devices with precisely controllable "on" times that can be mass produced and protracted "off" times compared to those prior art switches to allow the motor to cool sufficiently before resetting of the protective switch allowing restarting of the motor.
It is an object of this invention to provide a switch which is reliable in operation, has a minimum number of components and has a minimum amount of complexity.
It is another object of this invention to provide a thermostatic switch which is compact and therefore adapted for miniaturization so as to be conveniently inserted into the small spaces directly adjacent the heated parts of motors and the like.
It is another object of this invention to provide a thermostatic switch with a precisely controllable "on" time and a protracted "off" time.
It is yet another object of this invention to provide a thermostatic switch which is adapted for inexpensive manufacture.
It is still another object of this invention to provide a switch which is easily and simply calibrated.
Other objects will be in part apparent and in part pointed out hereinafter.
The invention accordingly comprises the elements and combinations of elements, features of construction and arrangement of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the following claims.